This invention relates to a spring hinge, and more particularly to an improved hinge construction incorporating a torsion spring for loading and release during the opening and closure of a door.
Spring hinges for urging a door into a normally closed position following opening are well known. Such automatic door closing devices are particularly useful in maintaining doors in a normally closed position to prevent the doors from being left open following use. The maintenance of such a closed position may be desirable in terms of both security and safety in the environment of use.
Spring hinges typically rely upon the loading and subsequent recovery of an internally disposed torsion spring. Due to the fact that individual hinges may be subjected to a variety of conditions so as to require greater or lesser force to achieve closure, it is known to use spring hinge door closing devices which are capable of adjustment to vary the torsional force on the spring and the corresponding force of closure exerted by the spring hinge on the door which it supports. One such prior adjustable spring hinge configuration is illustrated and described in U.S. Pat. No. 4,419,788 to Prout the teachings of which are incorporated herein by reference.
The known spring hinge construction described in U.S. Pat. No. 4,419,788 includes a pair of substantially opposed hinge leaves which are rotatable around a common axis defined by hollow knuckle portions which extend along adjacent edges and which are arranged in substantially axial alignment to form a hinge barrel in which a torsion spring is contained. Pintles located in each end of the hinge barrel extend through and between adjacent knuckles and slidingly engage opposing ends of the torsion spring such that the torsion spring is fixed against rotation relative to a knuckle of each respective hinge leaf A pre-loading torsion force may thus be established and adjusted by locking one pintle in place and thereafter rotating the other pintle relative to the first pintle to load the torsion spring. Once adjustment has taken place, a stop pin is inserted through an opening within the wall of the knuckle disposed in alignment with a pin opening in the adjustable pintle thereby holding the adjustable pintle at a predefined rotational position relative to the knuckle.
Since adjustment of the torsion spring typically takes place in the field, it is desirable to prevent the adjustable pintle from falling out of the hinge barrel prior to or during such adjustment. In the prior known embodiment, the adjustable pintle has been held in place relative to the hinge barrel by a thrust washer secured around a split bushing and disposed at the intersection between the knuckle elements. This combination of split bushings and a corresponding thrust washer thus provides an anti-friction surface between relatively moving metal parts of the door hinge while simultaneously preventing the pintle surrounded by the bushing and corresponding thrust washer from sliding out of the hinge barrel prior to insertion of an appropriate stop pin during adjustment of the torsion spring. The prior art constructions have thus required a relatively complex arrangement of components including multi-piece anti-friction elements which must be maintained in fixed relation to one another in order to carry out the requisite dual functions of friction reduction and containment of internal elements within the hinge barrel.
This invention provides advantages and alternatives over the prior art by providing a spring hinge assembly of substantially reduced complexity which is not dependent upon a multi-piece bushing and thrust washer assembly to hold the end torsion spring in place within the hinge barrel prior to torsion adjustment. More particularly, the present invention provides a spring hinge assembly in which a torsion spring is engageably locked between pintles such that engagement of one of the pintles at a fixed location within the hinge barrel causes the torsion spring and attached pintles to be retained within the hinge barrel thereby preventing inadvertent sliding removal of the pintles and/or the torsion spring prior to final adjustment of the torsion spring.
According to one aspect of the present invention a spring hinge is provided including a pair of hinge leaves having hollow knuckles on adjacent hinges which are arranged in substantially axial alignment such that the hollow knuckles comprise segments of a hinge barrel. A torsion spring made up of a resilient coiled spring member is housed within the hinge barrel. First and second pintles are disposed at opposing ends of the hinge barrel and extend into and between axially aligned knuckles of the hinge leaves. The first and second pintles each include a spring acceptance opening engaging the spring member such that the spring member extends in a substantially locked relation between the first and second pintles whereby torsion forces are translated between the torsion spring and the pintles. The pintles are held in place relative to the hinge barrel by pin members such that relative movement of the hinge leaves is translated to the pintles and to the torsion spring.
According to one potentially preferred embodiment of the invention a spring hinge is provided including a pair of hinge leaves having hollow knuckles on adjacent hinges arranged in substantially axial alignment such that the hollow knuckles comprise segments of a hinge barrel. A subassembly comprising a resilient torsion spring member of coiled wire with opposing pintles in locked relation at either end is housed within the hinge barrel such that the pintles are disposed at opposing ends of the hinge barrel and extend into and between axially aligned knuckles of the hinge leaves. Preferably, the torsion spring member is held in attached relation between the opposing pintles at the base of a split channel opening extending from the end of each pintle. The split channel opening preferably opens to an increased cross-sectional diameter at the base. The cross-sectional diameter at the base of the split channel opening is preferably slightly larger than the greatest cross-sectional dimension of the coiled wire such that the torsion spring member is not constrictingly pinched while residing at the base. The smaller cross-sectional diameter of the split channel opening below the base permits forced insertion of the wire into the base but substantially prevents manual separation of the spring member from the pintle following such insertion. Pin members hold the pintles in place relative to the hinge barrel such that relative movement of the hinge leaves is translated to the pintles and to the torsion spring.